1. Field of the Invention
The present invention relates to a semiconductor integrated circuit designing apparatus, a semiconductor integrated circuit designing method and a semiconductor device.
2. Related Background Art
In the manufacture of a semiconductor integrated circuit device, an instruction may be given to change its specification or add a function thereto after the making of a mask.
For signal wiring lines of a net added due to a change in a circuit after mask making, two wiring layers are generally used instead of changing all the layers in order to minimize the number of masks changed. The reason is that added logical elements are placed on the basis of global wiring in order to increase the wiring efficiency of signal line and to apply priority wiring directions in the context of the increase of layers in a semiconductor integrated circuit.
However, the problem of conventional techniques is that signal wiring lines of at least two layers are required and the number of masks changed often increases accordingly.